False positive with before_action set in class method

[mikegee]

This is a recreation of covermymeds/rubocop-thread_safety/issues/40 opened by @JasonBarnabe on Apr 2, 2021.

---

No offense reported

before_action {
  @my_var = 'foo'
}

Offense reported

def self.add_my_before_action
  before_action {
    @my_var = 'foo'
  }
end
add_my_before_action